The profile of human trafficking as a crime is rising as law-enforcement officials, lawmakers and celebrities press for action, victims and their advocates spotlight the issue and California stiffens penalties against traffickers after last week’s passage of Proposition 35.

There is still much more to accomplish in combating human trafficking, but the movement is gaining traction, experts said.

They liken its evolution to efforts to counter domestic violence since the 1980s. Back then, victims’ advocates were trying to educate law enforcement and communities on how to identify such violence and urging them to recognize it as a crime. Since then, domestic violence has been well documented, and systems are in place to help victims and their families.

Human trafficking — for labor and sex — ensnares 21 million to 27 million victims at any given time, generates an estimated $32 billion each year, and ranks in the top three global criminal enterprises, along with drug and arms trafficking.

The campaign against it gained momentum in September when President Barack Obama addressed the issue during a speech in New York.

“It adds more energy to the anti-trafficking movement,” said Sheldon Zhang, a sociologist at San Diego State University who is conducting research on trafficking in this region. “Labor trafficking is a gross violation of human rights.”

On Tuesday, the push against human trafficking gained more traction when Proposition 35 won 81 percent of the vote. The law increases prison time for convicted traffickers, requires them to register as sex offenders and mandates that sex offenders turn over all online user names and passwords to police.

That last stipulation prompted the Northern California American Civil Liberties Union and the Electronic Frontier Foundation to file a lawsuit last week.

“The ability to speak freely and even anonymously is crucial for free speech to remain free for all of us,” said Michael Risher, an ACLU attorney. “Stopping human trafficking is a worthy goal, but this portion of Prop. 35 won’t get us there.”

Supporters of the new law believe it will remain intact. They praise Californians for understanding the need to boost awareness, deterrence and punishment of human trafficking.

“Through this campaign, millions of Californians became aware that human trafficking is a crime that plagues our communities,” said Daphne Phung, founder of California Against Slavery and the driving force behind Proposition 35.

Obama’s speech on Sept. 25 at the Clinton Global Initiative was welcomed by Phung and others who have been toiling to bring attention to the issue for years. The president delivered his remarks just after the 150th anniversary of the introduction of the Emancipation Proclamation.

“The ugly truth is that trafficking goes on right here in the United States,” Obama said. “It’s the migrant worker unable to pay off his debt to his trafficker. It’s the man lured to America with the promise of a job, his documents taken and put to work in a kitchen. It’s the teenage girl beaten and forced to walk the streets. This should not be happening in the United States.”

Obama announced new strategies to fight human trafficking at home and abroad, including an executive order requiring stricter hiring guidelines for federal contractors and subcontractors; increased training for law enforcement, teachers and social workers; and a call to the private sector to get on board.

David Rogers, program manager for human trafficking in the civil-rights unit of the FBI, also emphasized that the crime happens not only in other countries.

“We are seeing victims (here) across all demographics — all races, genders, people here legally, U.S. citizens,” he said.

Based on the limited data currently available, the majority of sex-trafficking victims in the United States are Americans, while most labor-trafficking victims are migrants. Sex-trafficking cases get more attention, experts said, but labor trafficking — in fields, on construction sites, in private homes — is actually a much bigger problem.

“It’s not something that people want to report,” said Daniel Page, assistant special agent in charge for Immigration and Customs Enforcement in San Diego. “There is a lot of fear.”

Page’s office is collaborating with local nongovernmental organizations to find cases to investigate. It is part of his team’s efforts to build trust among victims so more of them come forward to seek help.

Obama’s appeal to private enterprise and philanthropists to get involved also should help victims, said U.S. State Department ambassador Luis CdeBaca, who oversees the Office to Monitor and Combat Trafficking in Persons.

The State Department issues an annual Trafficking in Persons report. In addition, next spring’s FBI uniform crime report will include statistics on human trafficking, CdeBaca said.

“It’s a first step,” he added. “This is a hidden crime, and victims don’t want to come forward, but it’s also hidden in the data.”